Mandrel means

ABSTRACT

Mandrel means for forming tubular tubular articles of an infinitely variable range of sizes by helical winding of strip material (25) around the mandrel means comprises a support surface defined by an endless belt (37) which extends around two support drums (36) the spacing of which is selectively variable. The mandrel means additionally comprises a belt guide assembly (38) (39) which preferably diverts the belt (37) to follow an inwardly extending path between the support drums (36) and thereby results in a peripheral discontinuity in the mandrel means support surface. The belt guide assembly may also incorporate a roller (39) to maintain tension in the belt (37) irrespective of the spacing of the support drums (36). Cutter means may be provided to cut a wound tubular article in the vicinity of the support surface discontinuity.

This is a continuation of application Ser. No. 07/474,133 filed May 1,1990.

This invention relates to a mandrel means and in particular, althoughnot exclusively, to a mandrel means suitable for use in the manufactureof reinforced ply fabric material of a kind utilised in the manufactureof radial or cross ply pneumatic tires. The invention relates also to amandrel means suitable for the production of a tubular article.

To produce tubular articles of a range of sizes by conventionaltechniques involving the use of a mandrel has the disadvantage that itis necessary to have available a range of mandrels ofcorrespondingly-related sizes. Apart from the cost associated with theneed to provide a number of mandrels there is the disadvantage of thenot insignificant time needed for interchanging mandrels when it isdecided to change the size of article being produced. Furthermore, thesizes of tubular article produced by the conventional technique is notinfinitely variable but is restricted to a size related to that of oneof the mandrels.

Particularly in the precision manufacture of certain types of flexiblereinforced polymeric articles, such as pre-sized sheets of ply fabricmaterial for use in automatic techniques for construction pneumatictires, it is desirable to be able to control and also selectively varythe size of the article within close tolerances.

The present invention seeks to provide mandrel means which readilyfacilitates small changes in the size of an article produced with theaid of the mandrel means.

In accordance with one of its aspects the present invention provides amandrel means comprising at least two support drums rotatably mountedfor rotation about respective axes the relative spacing of which isselectively variable to vary the length of a peripheral path defined atleast in part by said drums, an endless support belt which extendsaround said drums to define at least in part a mandrel support surface,and a belt guide means comprising a belt control device movable relativeto said drums and in engagement with the belt whereby the effectiveperipheral length of said mandrel support surface is variable inresponse to change of relative spacings of said support drums.

The belt control device may be movable to maintain a tension, preferablya substantially constant tension, in the endless belt for any of a rangeof relative spacings of said support drums. The belt control device maybe of a kind incorporating a spring-loaded member or like componentwhich serves to maintain tension automatically without the need foradjustment upon change of relative spacing of said support drums.

Preferably the belt guide means is a belt guide means assembly of a kindarranged to guide the belt whereby it defines a peripherallydiscontinuous mandrel support surface.

More preferably the belt guide means is an assembly comprising a pair ofguide rollers which divert the belt to follow an inwardly extending pathbetween the support drums and a belt control device in the form of atension roller for engaging a portion of belt between said guiderollers, the tension roller being movable relative to said guide rollersand support drums to maintain tension in the belt for any of a range ofrelative spacings of said support drums.

The endless belt may be of inextensible material and preferably isformed of reinforced polymeric material such as a rayon reinforcedsynthetic rubber material.

In mandrel means in which the endless belt defines a peripherallydiscontinuous mandrel support surface the region of the discontinuity inthe mandrel support surface may be employed to locate cutter means if itis desired to cut into a sheet a tubular article constructed on themandrel means. In such constructions the mandrel means may comprise acutter control device operable to control movement of a cutter means.The cutter control device may, for example, cause the cutter means tooperate only when the belt is not moving, or to move relative to thelength of the mandrel means at a speed related to the speed of movementof the belt if it is desired to attain, for example, an obliquelyextending cut.

The mandrel means additionally or alternatively may comprise anapplicator control device to control the supply of material to themandrel means, for example to control the supply of an elongatereinforced strip from a tape applicator to the mandrel means for helicalwinding around the mandrel means.

The invention also provides that the mandrel means may comprise liftingmeans such as a gas jet located in the region of the discontinuity inthe mandrel support surface and operable to lift relative to the mandrelmeans a cut edge of an initially tubular article formed on said mandrelmeans.

An embodiment of a mandrel means in accordance with the presentinvention will now be described by way of example in connection with themanufacture of textile ply fabric for the production of a radial plytire with reference to the accompanying diagrammatic drawings, in which:

FIG. 1 is a view of apparatus for forming tire fabric,

FIG. 2 is a sectional view of one form of the upper half of a tape,

FIG. 3 is a sectional view of the lower half of a tape which iscomplimentary to the top half shown in FIG. 2,

FIG. 4 is a sectional view of another form of the upper half of a tape,

FIG. 5 is a sectional view of the lower half of a tape which iscomplimentary to the top half shown in FIG. 4,

FIG. 6 is a sectional view of the composite consolidated tape producedby both forms shown in FIGS. 2, 3, 4 and 5,

FIG. 7 is an isometric view of a mandrel means in accordance with thepresent invention showing a completed tubular winding of tape,

FIG. 8 is a longitudinal sectional view of the final tubular ply fabricenvelope as it appears on the mandrel means showing the special endsproduced by use of a tape in the form shown in FIG. 6,

FIG. 9 is a view of the mandrel means at the ply cutting and removalstation showing a cutter and clamps for gripping the ply on thecarriage, prior to removal of the ply from the mandrel means,

FIG. 10 is a view of a six-roll calender looking downstream and showingmeans of adjusting the width of tape and means of adjusting the finalguage of the tape,

FIG. 11 is a plan view of the apparatus showing that the winding stationand the ply cutting/removal station may be part of a turret which mayconsist of one or more winding and ply cutting/removal stations, and

FIG. 12 is a plan view of an alternative layout showing a shuttlesystem, whereby one tape producing apparatus winds tape onto one orother of two mandrel means fitted to a carriage which is able to shuttlefrom one ply cutting/removal station to another.

Referring first to FIGS. 1-4, FIG. 1 shows a diagrammatic view ofapparatus in which pre-treated cords 1 are fed from cheeses or cones 2in a creel 46 (shown in FIG. 11) through individual tensioning units 3to a cord collecting frame 4.

At this point the cords may be divided into two sets of cords of manydifferent configurations, prior to being fed into the central nip of asix-roll calender 47 (shown in more detail in FIG. 11). Rubbery compoundproduced by two small cold feed extruders 48 (see FIG. 11) is introducedin rod form into the calender at two locations: firstly between calenderrolls 5 and 6 and secondly between rolls 7 and 8 (see FIG. 1).

A small rolling bank of compound (not shown) is maintained between rolls6 and 9 and between rolls 8 and 10, these paired rolls respectivelyproducing the upper 11 and lower 12 films of rubber for the constructionof the tape.

Rolls 5, 7, 9 and 10 are male rolls which fit closely inside the femalerolls 6 and 8. The rolls are constructed in such a manner that changesin width can quickly be achieved and bearing housings for the rolls aremounted in such a way that rubber guages can be changed easily.

An upper set of cords 13 from the collecting frame 4 passes over groovedguide and pressure roller 15, which embeds the cords into the rubberveneer 11 against the calender roll 9. Similarly a lower set of cords 14from the collecting frame 4 passes over a grooved guide and pressureroller 16 which embeds the cords into the rubber veneer 12 against thecalender roll 10.

The upper and lower sets of cords 13 and 14, respectively, are soarranged as to be complimentary to each other. For example, they may bearranged as shown in FIGS. 2 and 3, or FIGS. 4 and 5, or in a variety ofother ways including those described in our aforementioned copendingUnited Kingdom Patent Application of even date entitled "FlexibleReinforced Polymeric Material".

If either of the configurations shown by FIGS. 2-5 are used the finalform of the tape appears as shown in FIG. 6, with the upper and lowerrubber veneers 11, 12 transversely offset. The staggering of the upperand lower veneers 11, 12 is achieved by offsetting the upper half of thecalender with respect to the lower half, as shown in FIG. 10. Thisoffset is important in order to achieve the "jointless" plyconstruction.

The upper half of the calender, consisting of rolls 5, 6 and 9, is ableto move sideways as indicated by arrow A of FIG. 10 in order to achievethe offset. Geared motors 17 and 18 drive the upper and lower halves ofthe calender through respective gear sets 19, 20 and 21 and 22, 23 and24. The final nip between rolls 9 and 10 is adjustable by movement ofthe lower half of the calender in the direction of arrow D in order toachieve the desired thickness of the resulting composite ply fabric tape25. The ply fabric tape 25 is stripped off roll 10 by a contact roller26 and then passes through a festoon 27, which controls the speed of thecalender. The tape 25 is then fed to a tape applicator 28 which is ableto traverse in the direction of arrow B of FIG. 12 across the face of amandrel means, hereinafter referred to as a mandrel 29, parallel to itsaxis, by means of a driven leadscrew (not shown).

The tape applicator 28 may be raised and lowered as shown by thedirection of arrow C in FIG. 1 and contains a laying/pressure roller 30,a cutter unit 31, gripping roller 32 and guide rollers 33. Also mountedon the tape applicator 28 are a pair of guide rollers 34 which, togetherwith a similar pair of rollers 35 mounted on a fixed frame (not shown)positioned above and at a suitable distance from the lower rollers, turnthe tape through 90 degrees in order to accommodate the oscillation ofthe applicator across the face of the winding member in the direction ofarrow B.

The leading end of the tape 25 is laid onto the winding surface ofmandrel 29 by lowering the applicator 28 so that the laying/pressureroller 30 makes contact with the winding surface. The speed of rotationof the winding surface, the advancement of the applicator carriage andthe width of the tape are predetermined so as to give the correct amountof overlap of tape at each turn and the correct length of the envelopeacross the surface of the mandrel.

At the end of the run of tape 25 the mandrel stops in such a positionthat the end of the tape, when severed and laid on the surface, alignsaxially with the start of the tape. The envelope of the wound tape istransverse on the mandrel and is shown in cross section in FIG. 8.

The mandrel 29 comprises two drums 36. An endless belt 37 (see FIGS. 7and 9) is fitted around the two drums 36 and passes around a belt guidemeans assembly in the form of a take-up station consisting of two idlerrollers 38, a tension roller 39 and an air flotation unit 40. Thetension roller 39 is mounted in a spring-loaded device whereby theroller serves to maintain substantially constant tension in the beltirrespective of change of spacing of the support drums.

A complete range of ply widths, measured along the cords 1, may thus beobtained by suitable selection of drum centre distances.

At the ply cutting and removal station a driven circular knife 41 isbrought into a position (see FIG. 9) at which it cuts through the plyenvelope at an angle equal to the tape helix angle to give a 90 degreecut to the cord line.

During the cutting operation high pressure air is introduced to theflotation unit 40 to produce a gas (air) jet which raises the lip of theply material. This unit is used with low pressure air for the initialtransfer of the leading end of the tape across the gap in the belt atcommencement of helical winding. Having cut a plurality of ply piecesthe cutter may retract to its parked position 42 and a ply removalcarriage 43 (see FIGS. 9, 11 and 12) moves into position under themandrel.

A set of clamps 44 mounted on the carriage 43 grips the edge of the plymaterial and pulls the ply off the mandrel as the carriage movesoutwards. During this operation the ply material is accuratelypositioned onto a component carrier 45 on which the ply is transportedto the building drum of a tire building machine.

It will be appreciated from the above description that the presentinvention facilitates a rapid change and infinite adjustment of the sizeof fabric produced on the mandrel. Thus in the case, for example, offabric for use in applying to e.g. a tire building former rapid changeis possible by varying the total width of reinforcing tape woundhelically around the mandrel and by adjusting the peripheral dimensionof the mandrel.

I claim:
 1. Mandrel means; at least two support drums rotatably mountedfor rotation about respective axes the relative spacing of which isselectively variable to vary the length of a peripheral path defined atleast in part by said drums, a belt guide means assembly, an endlesssupport belt which extends around said drums and belt guide meansassembly and which defines at least in part a mandrel support surface,said belt guide means assembly comprising a pair of guide rollersarranged to divert the endless belt to follow an inwardly extending pathbetween the support drums and thereby result in a peripheraldiscontinuity of the mandrel support surface, and said belt guide meansassembly additionally comprising a belt control device to engage andmaintain tension in the belt for any of a range of relative spacings ofsaid support drums, and applicator means arranged for traversingmovement across the width of the endless belt for applying stripmaterial to the endless belt during movement of the endless belt aroundthe drums whereby the strip material is caused to extend helicallyrelative to said axes of rotation of the support drums.
 2. Mandrelmeans; at least two support drums rotatably mounted for rotation aboutrespective axes the relative spacing of which is selectively variable tovary the length of a peripheral path defined at least in part by saiddrums, an endless support belt which extends around said drums to defineat least in part a mandrel support surface, belt guide means comprisinga belt control device movable relative to said drums and in engagementwith the belt whereby the effective peripheral length of said mandrelsupport surface is variable in response to a change of relative spacingof said support drums, and applicator means arranged for traversingmovement across the width of the endless belt for applying stripmaterial to the endless belt during movement of the endless belt aroundthe drums whereby the strip material is caused to extend helicallyrelative to said axes of rotation of the support drums.
 3. Mandrel meansas claimed in claim 2, wherein the belt control device is movable tomaintain a tension in the endless belt for any of a range of relativespacings of said support drums.
 4. Mandrel means as claimed in claim 3,wherein the belt control device (39) is movable to maintain asubstantially constant tension in the endless belt.
 5. Mandrel means asclaimed in claim 3, wherein the belt control device is operable tomaintain tension in the belt automatically upon change of relativespacing of said support drums.
 6. Mandrel means as claimed in claim 2,wherein said belt guide means is a belt guide means assembly whichguides the endless belt to define a peripherally discontinuous mandrelsupport surface.
 7. Mandrel means as claimed in claim 6, wherein thebelt comprises reinforced polymeric material and the belt guide meansassembly comprises a pair of guide rollers arranged to divert theendless belt to follow an inwardly extending path between the supportdrums.
 8. Mandrel means as claimed in claim 7, wherein the belt guidemeans assembly comprises a belt control device to engage and maintaintension in the endless belt for any of a range of relative spacings ofsaid support drums.
 9. Mandrel means as claimed in claim 8, wherein thebelt control device engages an inward portion of the endless belt lyingbetween the guide rollers.
 10. Mandrel means as claimed in claim 9,wherein the belt control device (30) is a roller movable relative to atleast one of said support drums.
 11. Mandrel means as claimed in claim 1wherein it comprises a cutter control device operable to controlmovement of a cutter means in the region of the discontinuity in themandrel support surface.
 12. Mandrel means as claimed in claim 11,wherein the cutter control device is operable to cause cutter means tomove at a speed related to the speed of movement of the belt. 13.Mandrel means as claimed in claim 11, and wherein it comprises liftingmeans located in the region of the discontinuity in the mandrel supportsurface and operable to lift relative to the mandrel surface a cut edgeof an initially tubular article formed on said mandrel means. 14.Mandrel means as claimed in claim 13, wherein said lifting meanscomprises a gas jet.
 15. Mandrel means as claimed in claim 1, whereinsaid belt control device (39) engages an inward portion of the endlessbelt (37) lying between the guide rollers (38).
 16. Mandrel means asclaimed in claim 1, wherein the belt control device (39) is a rollermovable relative to at least one of said support drums (36).
 17. Mandrelmeans as claimed in claim 3, wherein the belt control device (39) is aroller movable relative to at least one of said support drums (36). 18.Mandrel means as claimed in claim 8, wherein the belt control device(39) is a roller movable relative to at least one of said support drums(36).